試題詳解

44. A rectangular coil with 1000 turns has a length and width of 10 cm and 20 cm respectively and carries a counterclockwise current of 10 A. When the magnetic dipole moment makes an angle of 60° with a magnetic field of 0.5 T, what is its potential energy?
(A) -50 J
(B) -87 J
(C) -100 J
(D) 50 J
(E) 100 J